Heat storage devices can be fabricated from a phase change material that can be a salt hydrate or an organic molecule and a container. The phase change material is placed in a tank or melted into a high thermal conductivity porous structure that is in a container. When the container absorbs heat, the phase change material absorbs the heat and melts if the temperature is above the phase change temperature. When the temperature drops below the phase change temperature, the material goes through a reverse phase change and releases heat. This is advantageous because a reduced weight and smaller heat sink may be used in a device as not all the heat must be radiated. However, in most thermal storage devices, extra weight is added to a component because heat storage devices cannot support weight and must be bolted onto the supporting structure rather than being part of it.
Also, heat exchangers transfer heat from a fluid or air stream to another fluid or air stream. They work best when they contain narrow pores (under 0.5 mm in diameter) with high aspect ratios. Pores with a large aspect ratio and small diameter are difficult to form.
Furthermore, heat storage systems may use a graphite felt or metal tank to move heat between an exterior environment and a phase change material; however, the tanks and graphite felt do not support the structure of the vehicle or component in which they are integrated. Additionally, these materials are not templated from a supporting structure that efficiently uses space to maximize the amount of phase change or thermal storage material to be contained and/or stored while remaining mechanically robust.
Heat exchangers may also be formed from a porous foam or honeycomb to transfer heat between two materials. However, for such heat exchangers, it may be difficult to fabricate high aspect ratio thin diameter pores with porosity of the desired dimensions.